/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hive.common;

import com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.conf.HiveConf.ConfVars;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.config.Configurator;
import org.apache.logging.log4j.core.impl.Log4jContextFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.net.URL;

/**
 * Utilities common to logging operations.
 */
public class LogUtils {
    
    private static final String HIVE_L4J = "hive-log4j2.properties";
    private static final String HIVE_EXEC_L4J = "hive-exec-log4j2.properties";
    private static final Logger l4j = LoggerFactory.getLogger(LogUtils.class);
    
    /**
     * Constants for log masking
     */
    private static final String KEY_TO_MASK_WITH = "password";
    private static final String MASKED_VALUE = "###_MASKED_###";
    
    @SuppressWarnings("serial")
    public static class LogInitializationException extends Exception {
        public LogInitializationException(String msg) {
            super(msg);
        }
    }
    
    /**
     * Initialize log4j.
     *
     * @return an message suitable for display to the user
     * @throws LogInitializationException if log4j fails to initialize correctly
     */
    public static String initHiveLog4j() throws LogInitializationException {
        return initHiveLog4jCommon(HiveConf.ConfVars.HIVE_LOG4J_FILE);
    }
    
    /**
     * Initialize log4j for execution mode.
     *
     * @return an message suitable for display to the user
     * @throws LogInitializationException if log4j-exec fails to initialize correctly
     */
    public static String initHiveExecLog4j() throws LogInitializationException {
        return initHiveLog4jCommon(HiveConf.ConfVars.HIVE_EXEC_LOG4J_FILE);
    }
    
    private static String initHiveLog4jCommon(ConfVars confVarName) throws LogInitializationException {
        HiveConf conf = new HiveConf();
        return initHiveLog4jCommon(conf, confVarName);
    }
    
    @VisibleForTesting
    public static String initHiveLog4jCommon(HiveConf conf, ConfVars confVarName) throws LogInitializationException {
        if (HiveConf.getVar(conf, confVarName).equals("")) {
            // if log4j configuration file not set, or could not found, use default setting
            return initHiveLog4jDefault(conf, "", confVarName);
        } else {
            // if log4j configuration file found successfully, use HiveConf property value
            String log4jFileName = HiveConf.getVar(conf, confVarName);
            File log4jConfigFile = new File(log4jFileName);
            boolean fileExists = log4jConfigFile.exists();
            if (!fileExists) {
                // if property specified file not found in local file system
                // use default setting
                return initHiveLog4jDefault(conf, "Not able to find conf file: " + log4jConfigFile, confVarName);
            } else {
                // property speficied file found in local file system
                // use the specified file
                if (confVarName == HiveConf.ConfVars.HIVE_EXEC_LOG4J_FILE) {
                    String queryId = HiveConf.getVar(conf, HiveConf.ConfVars.HIVEQUERYID);
                    if (queryId == null || (queryId = queryId.trim()).isEmpty()) {
                        queryId = "unknown-" + System.currentTimeMillis();
                    }
                    System.setProperty(HiveConf.ConfVars.HIVEQUERYID.toString(), queryId);
                }
                final boolean async = checkAndSetAsyncLogging(conf);
                Configurator.initialize(null, log4jFileName);
                logConfigLocation(conf);
                return "Logging initialized using configuration in " + log4jConfigFile + " Async: " + async;
            }
        }
    }
    
    public static boolean checkAndSetAsyncLogging(final Configuration conf) {
        final boolean asyncLogging = HiveConf.getBoolVar(conf, ConfVars.HIVE_ASYNC_LOG_ENABLED);
        if (asyncLogging) {
            System.setProperty("Log4jContextSelector", "org.apache.logging.log4j.core.async.AsyncLoggerContextSelector");
            // default is ClassLoaderContextSelector which is created during automatic logging
            // initialization in a static initialization block.
            // Changing ContextSelector at runtime requires creating new context factory which will
            // internally create new context selector based on system property.
            LogManager.setFactory(new Log4jContextFactory());
        }
        return asyncLogging;
    }
    
    private static String initHiveLog4jDefault(
            HiveConf conf, String logMessage, ConfVars confVarName) throws LogInitializationException {
        URL hive_l4j = null;
        switch (confVarName) {
            case HIVE_EXEC_LOG4J_FILE:
                hive_l4j = LogUtils.class.getClassLoader().getResource(HIVE_EXEC_L4J);
                if (hive_l4j == null) {
                    hive_l4j = LogUtils.class.getClassLoader().getResource(HIVE_L4J);
                }
                System.setProperty(HiveConf.ConfVars.HIVEQUERYID.toString(), HiveConf.getVar(conf, HiveConf.ConfVars.HIVEQUERYID));
                break;
            case HIVE_LOG4J_FILE:
                hive_l4j = LogUtils.class.getClassLoader().getResource(HIVE_L4J);
                break;
            default:
                break;
        }
        if (hive_l4j != null) {
            final boolean async = checkAndSetAsyncLogging(conf);
            Configurator.initialize(null, hive_l4j.toString());
            logConfigLocation(conf);
            return (logMessage + "\n" + "Logging initialized using configuration in " + hive_l4j + " Async: " + async);
        } else {
            throw new LogInitializationException(logMessage + "Unable to initialize logging using " + LogUtils.HIVE_L4J + ", not found on " +
                    "CLASSPATH!");
        }
    }
    
    private static void logConfigLocation(HiveConf conf) throws LogInitializationException {
        // Log a warning if hive-default.xml is found on the classpath
        if (conf.getHiveDefaultLocation() != null) {
            l4j.warn("DEPRECATED: Ignoring hive-default.xml found on the CLASSPATH at " + conf.getHiveDefaultLocation().getPath());
        }
        // Look for hive-site.xml on the CLASSPATH and log its location if found.
        if (conf.getHiveSiteLocation() == null) {
            l4j.warn("hive-site.xml not found on CLASSPATH");
        } else {
            l4j.debug("Using hive-site.xml found on CLASSPATH at " + conf.getHiveSiteLocation().getPath());
        }
    }
    
    /**
     * Returns MASKED_VALUE if the key contains KEY_TO_MASK_WITH or the original property otherwise.
     * Used to mask environment variables, and properties in logs which contain passwords
     *
     * @param key   The property key to check
     * @param value The original value of the property
     * @return The masked property value
     */
    public static String maskIfPassword(String key, String value) {
        if (key != null && value != null) {
            if (key.toLowerCase().indexOf(KEY_TO_MASK_WITH) != -1) {
                return MASKED_VALUE;
            }
        }
        return value;
    }
}
